Acoustic pianos such as conventional grand pianos and upright pianos are composed of many parts. Further, since the assembly of these parts is of high complexity, the assembling work takes a long time. In particular, the assembly of an action mechanism that is provided in correspondence with each key is of high complexity, as the action mechanism requires many parts.
For example, Japanese Patent Application Laid-Open No. 2005-292361 discloses an action mechanism in which a plurality of parts interact with one another to transmit, to a hammer, the movement of a key being pressed and released. In particular, a part of the action mechanism is constituted by a support assembly that works through a combination of various parts. The support assembly includes not only a mechanism that achieves the striking of the string by the hammer according to the pressing of the key but also an escapement mechanism by which the force to be transmitted to the hammer is released through the movement of the key immediately before the striking of the string. This mechanism is an important mechanism for achieving the basic movements of an acoustic piano. In particular, a conventional grand piano employs a double escapement mechanism including a combination of a repetition lever and a jack.
The movement of the action mechanism gives sensation (hereinafter referred to as “feeling of touch”) to the player's finger through the key. In particular, the configuration of the support assembly has an important influence on the feeling of touch. For example, the feeling of touch through the movement of the escapement mechanism is called “let-off”.